1. Field of the Invention
The present invention pertains to a radiographic imaging device, a computer-readable medium storing a program for controlling a radiographic imaging device, and a method for controlling radiographic imaging device. The present invention particularly relates to a radiographic imaging device, a computer-readable medium storing a program for radiographic imaging device, and a method for controlling radiographic imaging device, that images radiographic images for medical purposes.
2. Description of the Related Art
Generally, radiographic imaging devices that perform radiographic imaging for medical diagnoses have been known. The radiographic imaging devices image radiographic images by detecting radiation that has been irradiated from a radiation irradiation device and has passed through a subject. The radiographic imaging devices perform image of radiographic images by collecting and reading out charges that have been generated in response to the irradiated radiation.
Such conventional radiographic imaging devices are equipped with a radiation detection element that detects the radiation. Examples of the radiation detection element include a radiation detection element including photoelectric conversion elements, switching elements, and amplifier circuits, that are arrayed two-dimensionally. The photoelectric conversion elements generate charges as a result of radiation, or light into which radiation has been converted, being irradiated or illuminated to the photoelectric conversion elements. The switching elements read-out the charges that have been generated in the photoelectric conversion elements and output electric signals corresponding to the charges. The amplifier circuits includes integrator circuits that accumulate the charges corresponding to the electric signals that have been outputted from the switching elements and output electric signals in which the accumulated charges have been amplified.
The radiation detection element has a configuration where, like a TFT active matrix substrate, plural gate lines (scan lines) and plural signal lines are arranged intersecting each other, and therefore, may cause a parasitic capacitance. The gate lines (scan lines) switch the switching elements ON and OFF. The signal lines transmit charges from pixels whose switching elements have been switched ON. Consequently, at the time when the switching elements are ON and at the time when the switching elements are OFF, the size of the voltage applied to the parasitic capacitance existing in the positions where the signal lines intersect the scan lines connected to those switching elements changes. Due thereto, inductive charges occur in the parasitic capacitance, and the inductive charges may be superimposed on the charges (signal charges for a radiographic image) transmitted through the signal lines, as a noise component called feed through. The charge quantities held and accumulated in individual pixels in a radiation detection panel are minute, and the order of the feed-through are the same as the order of the signal charges transmitted through the signal lines. For this reason, the feed-through component may bring a measurable affects. Particularly in the case of imaging moving-image, the dose per imaging is made smaller than in imaging still-image. Accordingly, the charge quantities held and accumulated in the pixels become even small and the effect of the feed-through component becomes larger.
Examples of technologies to remove (cancel) the feed-through are described in Japanese Patent Application Laid-Open (JP-A) No. 2001-56382, JP-A No. 2006-101396, and JP-A No. 2007-108082.
JP-A No. 2001-56382 describes a technology that cancels feed-through by dedicated adjusting sections that are separately arranged. Further, in JP-A No. 2006-01396, there is described a technology that cancels the feed-through. This technology includes charge amp as a differential amp for performing correlated double sampling and, within the charge signals integration time period in the amp, outputs to each gate line a voltage that is the inverse of the voltage of control signals that switches the switching elements to an ON state. Due thereto, this technology cancels the feed-through component with a control signals for switching the switching elements ON, and control signals for switching the gates OFF within one integration time period. Further, JP-A No. 2007-108082 discloses a technology where selection switches are disposed on the signal lines, and where the feed-through component is canceled within one integration time period by the ON/OFF operation of the selection-use switches and the gate lines.
However, in the technology described in JP-A No. 2001-56382, the dedicated adjusting sections are necessary. Accordingly, in this technology, dedicated circuits and so forth are necessary for the dedicated adjusting sections. Further, in this technology, in order to avoid the superimposition of sensitivity information on the dedicated adjusting sections, sensor capacitances cannot be added, and the capacitances end up differing. Further still, it is necessary for the dedicated adjusting sections to be placed in neighboring portions of the switching elements (pixels), so in a large-area sensor substrate, the capacitances end up varying in-plane.
On the other hand, in the technology described in JP-A No. 2006-101396, electric signals where the feed-through component has been superimposed on the signal charges are inputted to the amplifier circuit that accumulates the charges. Consequently, in this technology, the electric signals end up not fitting in the range amplifiable by the integrator circuits (amps) of the amplifier circuits, whereby the dynamic range becomes narrower.
Further, in the technology described in JP-A No. 2007-108082, the accumulation of the charges in the integrator circuits starts from the time when the selection switches have been switched ON. For this reason, in this technology, the dynamic range becomes narrower because of switching noise resulting from the selection switches, and switching noise resulting from the gates of the TFTs that are being ON.